微波消解-石墨炉原子吸收光谱法测定胶囊中的痕量铬

研究了微波消解-石墨炉原子吸收光谱法测定胶囊中痕量铬的方法.选择HNO3作为微波消解的酸,通过干扰试验,发现该方法的选择性满足要求.方法线性关系良好,相关系数r2=0.999 8,检出限为1.7×10-14g,测定结果的相对标准偏差为2.63%(n=7),加标回收率为95.0%～104.0%.方法灵敏度高,重复性好,适...     

Study of the separation and determination of monosaccharides in soluble coffee by capillary zone electrophoresis with electrochemical detection

A simple, fast and reliable method, based on capillary electrophoresis with electrochemical detection, for the separation and determination of six monosaccharides, namely glucose, galactose, arabinose, fructose, xylose and ribose, in soluble coffees was developed. A copper disk electrode was used as the working electrode. The optimum conditions for separation and detection were 50 mmol L-1 sodium hydroxide buffer (pH 12.7), separation voltage 5 kV and detection potential 0.65 V (vs. Ag/AgCl). The linear ranges were from 5.0 x 10(-3) to 0.5 mmol L-1 for all six sugars. All regression coefficients were > 0.99. The detection limits for all the sugars were 1.0 x 10(-3) mmol L-1. The RSD of the peak current was < 4.2% (n = 5). The proposed method was applied directly to the separation and determination of the six sugars without prior derivatization, and the assay results were satisfactory.     

石墨炉原子吸收光谱法测定中药口服液中的铬铅镉

利用石墨炉原子吸收光谱法测定,采用常温消解和密闭微波消解等方式处理口服液样品,并进行比较。结果表明,采用HNO3 HClO4 H2O2作为消解试剂用常温消解方式进行消解后,可不加基体改进剂直接进行测定,在此基础上研究了石墨炉原子吸收测定的最佳条件。应用这种方法测定了双黄连、清开灵、生脉饮和抗病毒口服液中痕量镉、铬和铅,RSD小于5．0％,回收率在83．4％～113％。     

烘箱消解-镉铜还原法测定地表水中总氮

提出了烘箱消解-镉铜还原法测定地表水中总氮含量的方法。氮的浓度在7.637×10-4～1.375×10-2 mmol.L-1范围内与其吸光度呈线性关系,检出限(3S/N)为6.704×10-5 mmol.L-1。对人工海水、实验室自来水、海水和湖水中总氮进行测定,其回收率和相对标准偏差(n=6)分别在96.7%～101.3%和3.7%～3.9%之间。     

Preparation of starch and other carbon fractions from higher plant leaves for stable carbon isotope analysis.

The measurement of the carbon isotope composition of starch and cellulose still relies on chemical isolation of these water-insoluble plant constituents and subsequent elemental analysis by isotope ratio mass spectrometry (EA/IRMS) of the purified fractions, while delta(13)C values of low-molecular-weight organic compounds are now routinely measured by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Here we report a simple and reliable method for processing milligram quantities of dried plant material for the analysis of the carbon isotope composition of lipids, soluble sugars, starch and cellulose from the same sample. We evaluated three different starch preparation methods, namely (1) enzymatic hydrolysis by alpha-amylase, (2) solubilization by dimethyl sulfoxide (DMSO) followed by precipitation with ethanol, and (3) partial hydrolysis by HCl followed by precipitation of the resulting dextrins by ethanol. Starch recovery for three commercially available native starches (from potato, rice and wheat) varied from 48 to 81% for the techniques based on precipitation, whereas the enzymatic technique exhibited yields between 99 and 105%. In addition, the DMSO and HCl techniques introduced a significant (13)C fractionation of up to 1.9 per thousand, while the carbon isotope composition of native starches analyzed after enzymatic digestion did not show any significant difference from that of untreated samples. The enzymatic starch preparation method was then incorporated into a protocol for determination of delta(13)C signatures of lipids, soluble carbohydrates, starch and crude cellulose. The procedure is based on methanol/chloroform/water extraction of dried and ground leaf material. After recovery of the chloroform phase (lipid fraction), the methanol/water phase was deionized by ion exchange (soluble carbohydrate fraction) and the pellet treated with heat-stable alpha-amylase (starch fraction). The remaining insoluble material was subjected to solvolysis by diglyme (cellulose fraction). The method was shown to be applicable to foliar tissues of a variety of different plant species (spruce, erect brome, maize and soybean).     

电感耦合等离子体质谱法测定香精香料中的硼元素

采用微波消解-电感耦合等离子体质谱法(ICP-MS)测定香精香料中硼元素的含量。对微波消解样品前处理条件和仪器参数进行了优化,该方法硼元素检出限为1.005 ng/mL、平均回收率为106.1%、精密度为6.15%(n=5),并用茶叶国家标准物质(GBW10016)对分析方法进行了校准。该方法适合于香精香料中硼元素的测定。     

Preparation of starch and soluble sugars of plant material for the analysis of carbon isotope composition: a comparison of methods

Starch and soluble sugars are the major photosynthetic products, and their carbon isotope signatures reflect external versus internal limitations of CO₂ fixation. There has been recent renewed interest in the isotope composition of carbohydrates, mainly for use in CO₂ flux partitioning studies at the ecosystem level. The major obstacle to the use of carbohydrates in such studies has been the lack of an acknowledged method to isolate starch and soluble sugars for isotopic measurements. We here report on the comparison and evaluation of existing methods (acid and enzymatic hydrolysis for starch; ion‐exchange purification and compound‐specific analysis for sugars). The selectivity and reproducibility of the methods were tested using three approaches: (i) an artificial leaf composed of a mixture of isotopically defined compounds, (ii) a C₄ leaf spiked with C₃ starch, and (iii) two natural plant samples (root, leaf). Starch preparation methods based on enzymatic or acid hydrolysis did not yield similar results and exhibited contaminations by non‐starch compounds. The specificity of the acidic hydrolysis method was especially low, and we therefore suggest terming these preparations as HCl‐hydrolysable carbon, rather than starch. Despite being more specific, enzyme‐based methods to isolate starch also need to be further optimized to increase specificity. The analysis of sugars by ion‐exchange methods (bulk preparations) was fast but produced more variable isotope compositions than compound‐specific methods. Compound‐specific approaches did not in all cases correctly reproduce the target values, mainly due to unsatisfactory separation of sugars and background contamination. Our study demonstrates that, despite their wide application, methods for the preparation of starch and soluble sugars for the analysis of carbon isotope composition are not (yet) reliable enough to be routinely applied and further research is urgently needed to resolve the identified problems. Copyright © 2009 John Wiley & Sons, Ltd.     

Quantification of sugars and organic acids in hygroscopic pharmaceutical herbal dry extracts

Three chromatographic methods have been employed for the determination of hydrophilic compounds, namely carbohydrates and organic acids in herbal dry extracts of Eschscholtzia californica Cham. The hydrophilic compounds were separated from the other components of the dry extracts by solid-phase extraction methods, which were optimised with respect to recovery rates. Carbohydrates were quantified using high-performance anion-exchange chromatography with pulsed amperometric detection. Organic acids were analysed by ion-exclusion chromatography with evaporative light scattering detection and gas chromatography-mass spectrometry. Using the latter method, large amounts of glyceric acid were separated from the extracts of Eschscholtzia californica Cham. This substance together with sugars may be responsible for the increased hygroscopicity and the poor processing behaviour of the extracts.     

ICP-AES测定铀污染土壤植物中铀的研究

采用电感耦合等离子体发射光谱(ICP-AES)对铀污染土壤植物中铀的测定方法进行了研究.在λU385.958 nm处,选择了仪器的最佳工作条件,考察了酸度和常见共存元素对测定的干扰情况,并且对比了干灰化消解和湿式消解对测定的影响.研究发现2%硝酸溶液为最佳介质,干扰离子对测定没有显著影响,干灰化消解比湿式消解得彻底.在选定条件下,方法检出限为0.18 mg·L-1,测定下限为0.61 mg·L-1,5.0000 mg·L-1的铀标准溶液的相对标准偏差RSD(n=10)为0.81%,方法回收率为96.2%～106.2%.该方法操作简单,快速.结果表明,用ICP-AES测定铀污染土壤植物样品中的铀是可行的.     

Liquid chromatographic determination of less polar ginsenosides in processed ginseng

A novel method for the determination of iodide by size exclusion chromatography was established. The method was simple and highly sensitive with good precision. Iodide was converted to iodine, then sequestered with starch, and separated from the matrix using a Shim-pack DIOL-150 (250 x 7.9 mm) size exclusion column with methanol-0.01 mol l(-1) aqueous phosphoric acid (10:90, v/v) as mobile phase at 1.2 ml min(-1) and UV detection at 224 nm. The calibration graph was linear from 1.0 ng ml(-1) to 100.0 ng ml(-1) for iodide with a correlation coefficient of 0.9992 (n=6). The detection limit was 0.2 ng ml(-1). The method was successfully applied to the determination of iodide in seawater and urine. The recovery was from 92% to 103% and the relative standard deviation was in the range of 1.5% to 3.7%.     

微波密闭消解-ICP-MS－标准加入法测定矿石中金和银

建立了微波密闭消解-电感耦合等离子体质谱法(ICP-MS)采用标准加入法测定矿石中痕量元素金和银。考察了微波试样消解、基体效应、质谱干扰,并进行了ICP离子源以及质谱仪检测条件和微波消解参数的最优化。以标准加入法消除复杂多变的矿石基体对分析信号的影响,干扰校正方程消除多原子离子等质谱重叠影响。本法测定矿石中金银结果表明:回收率为197Au 106%～113%、107Ag 95%～105%、 109Ag 93%～103%,相对标准偏差RSD <6%（n=8）,检测限197Au为10 ng/g、107Ag为3 ng/g、109Ag为6 ng/g。方法适用性强,可满足不同类型矿石中超痕量金银的测定,分析步骤少,操作简便,快捷准确     

Fast microwave-assisted free sugars washing and hydrolysis pre-treatment for the flow injection determination of starch in food

The approach used consists of a flow injection (FI) manifold assisted by a focused microwave digestor for both fast washing of free sugars and acceleration of the hydrolysis step prior to the determination of starch in food. The action of microwaves reduces both the times for removal of free sugars to a 5 min single washing cycle with ethanol/water and that of the subsequent starch hydrolysis to a 10 min step. The sugars formed in the starch hydrolysis are in-line derivatised and photometrically monitored at λ=460 nm. In this way, automation of pre-treatment and determination is achieved with the minimum of both cost and time. The precision of the overall method, expressed as relative standard deviation, is 3.75% and the total analysis time is 38 min. Comparison of the results, obtained in applying the method to flour and bread, is in agreement with those provided by the manual method.     

Measurement of sugars and starches in foods by a modification of the AOAC total dietary fiber method.

A separation scheme for the determination of sugars and starch in processed food was developed. It is based on AOAC Method 985.29 for total dietary fiber with these modifications: carbohydrate starches are separated into soluble and insoluble fractions before they are hydrolyzed; acetonitrile is used instead of ethanol to separate sugars from enzyme-resistant carbohydrates, proteins, and other macromolecules; and a solid-phase extraction filter is included to remove substances that interfere with high-performance liquid chromatography (HPLC). Recovery studies indicate a > 97% sugar recovery. Twenty foods were analyzed. After enzymatic hydrolysis, fructose, glucose, sucrose, maltose, and lactose were extracted and determined by HPLC using a refractive index detector. Starch content was calculated from the increase in the amount of glucose. The results were compared with values listed on the "Nutrition Facts" panel for that food. The analyzed amounts of sugars and starches were 73-96% of declared values.     

Therapeutic drug monitoring of albendazole: determination of albendazole, albendazole sulfoxide, and albendazole sulfone in human plasma using nonaqueous capillary electrophoresis

A nonaqueous capillary electrophoretic method (NACE) for the fast determination of plasma levels of albendazole (ABZ), albendazole sulfoxide (ABZSO), and albendazole sulfone (ABZSO2) is described. The assay is based upon liquid/liquid extraction of these compounds using dichloromethane at pH 10.2 (recovery between 63 and 98%), followed by a NACE separation performed within 8 min employing a 0.036 M borate buffer (apparent pH 9.9) in a mixture of methanol and N-methylformamide (1:3) and on-column absorbance detection at 280 nm. Using 0.5 mL of plasma and extract reconstitution in 200 microL N-methylformamide, drug levels between 1.0-10 microM were found to provide linear calibration graphs. Intraday and interday imprecisions evaluated from peak area ratios (n = 5) were <10% and <12%, respectively. Corresponding imprecisions of detection times (n = 5) were <1% and <6%, respectively. The limit of detection (LOD) for ABZ, ABZSO and ABZSO2 was 8 x 10(-7) M. The reliability of the method developed was verified via analysis of 45 plasma samples obtained from patients treated with ABZ. Good agreement was obtained between the levels of ABZSO and those determined by routine HPLC. ABZ was found to be undetectable in all patient samples, whereas the levels of ABZSO2 were below or close to LOD.     

微波消解-原子荧光光谱法测定海洋生物体中汞

应用原子荧光光谱法测定海洋生物体中汞的含量。试样用盐酸、硝酸和过氧化氢混合溶液在微波消解仪中消解处理,经试验选定消解程序为:①消解功率1 600 W;②5min升温至120℃,保持5min;③5min升温至160℃,保持10min。分析时仪器工作条件为负高压260V,灯电流为40mA,载气流量为800mL.min-1。汞的质量浓度在0.80μg.L-1以内与相应的荧光强度呈线性关系,方法检出限(3s/k)为0.002mg.kg-1。方法用于测定海洋生物体中汞的含量,测定值的相对标准偏差(n=6)在2.7%～6.0%之间,加标回收率在90%～104%之间。     

CE Determination of Carbohydrates Using a Dipeptide as Separation Electrolyte

The influence of aminoacid and peptide type buffers as the separation electrolyte to the resolution of underivatized neutral carbohydrates in capillary electrophoresis was investigated. With the use of plain glycylglycine as the background electrolyte, a noticeable improvement in the resolution of carbohydrates was observed. Without any additive, 50 mmol L⁻¹ glycylglycine electrolyte at pH 12 provides both the fast separation and indirect detection of sugars. The electrophoretic mobilities of 16 sugars were calculated at this buffer and the combinations of 10 sugars were simultaneously detected. The method was applied to the determination of sucrose, glucose, and fructose in commercial juice samples.     

Development and validation of gas chromatography-mass spectroscopy method for determination of prilocaine HCl in human plasma using internal standard methodology

The accurate determination of prilocaine HCl levels in plasma is important in both clinical and pharmacological/toxicological studies. Prilocaine HCl is quickly hydrolyzed to o-toluidine, causing methemoglobinemia. For this, the present work describes the methodology and validation of a GC-MS assay for determination of prilocaine HCl with lidocaine HCl as internal standard in plasma. The validation parameters of linearity, precision, accuracy, recovery, specificity, limit of detection and limit of quantification were studied. The range of quantification for the GC-MS was 20-250 ng/mL in plasma. Within-day and between-day precision, expressed as the relative standard deviation (RSD) were less than 6.0%, and accuracy (relative error) was better than 9.0% (n = 6). The analytical recovery of prilocaine HCl and IS from plasma has averaged 94.79 and 96.8%, respectively. LOQ and LOD values for plasma were found to be 20 and 10 ng/mL, respectively. The GC-MS method can be used for determination from plasma of prilocaine HCl in routine measurement as well as in pharmacokinetic studies for clinical use.     

超高效液相色谱法测定卷烟烟丝中7种水溶性糖含量

以ACQUITY UPLC BEH Amide柱为分析柱,乙腈－0．2％三乙胺一水作为流动相,建立了超高效液相色谱－蒸发光散射检测器测定卷烟烟丝中鼠李糖、木糖、果糖、甘露糖、葡萄糖、蔗糖、麦芽糖7种水溶性糖的分析方法。7种水溶性糖回归方程的线性相关系数均大于0．999,检出限为0．56～1．11μg／mL。7种水溶糖的回收率在90．43％106．41％之间,相对标准偏差为1．66％－4．35％仰：6）。该方法灵敏度、准确度高,稳定性好,可用于大批量卷烟烟丝中水溶性糖含量的测定。     

薄层色谱-紫外分光光度法测定 溴敌隆乳油中的有效成份

用薄层色谱－紫外分光光度法分离和测定溴敌隆乳油中的有效成份,样品以甲醇－乙酸乙酯－石油醚（10：20：8）为展开剂在硅胶G板上展开,在波长262nm处测定分析,方法在0.25－1.50mg/mL范围内有良好的线性关系,检出限为0.08mg/mL,RSD值为1.9%(n=10),回收率97.1%-102.1%。     

Determination of vitamin K1 in medical foods by liquid chromatography with postcolumn reduction and fluorometric detection

A liquid chromatographic (LC) method is described for the determination of vitamin K1 in medical foods. The sample is enzymatically digested with lipase and alpha-amylase and extracted with 1% sodium bicarbonate solution-isopropanol (1 + 1). After C18 solid-phase extraction, vitamin K1 is separated by nonaqueous reversed-phase LC, converted to the hydroquinone by postcolumn zinc reduction, and quantitated by fluorescence detection. The limit of detection is 8 pg (3 sigma), and the limit of quantitation is 27 pg (10 sigma) on column. Linear response ranged from 0.1 to 1.0 ng vitamin K1 (r= 0.9999). The mean recovery (n = 38) for all spiking levels was 101.6 +/- 2.85%. Analysis of Standard Reference Material 1846, Infant Formula, gave a mean value of 0.95 +/- 0.088 mg vitamin K/kg (K or K1?) (n = 31) with a coefficient of variation of 9.26.